JP2016225494A - Fluorescent material containing composition and led device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorescent material containing composition capable of forming a fluorescent material containing layer, excellent in light fastness, hardly generating coloring caused by irradiation of ultraviolet light.SOLUTION: The composition for forming a fluorescent material containing layer for covering a light-emitting surface of an LED device includes: a resin containing a fluorine resin (I); a fluorescent material; an aqueous medium; and an emulsifier. The content of the emulsifier is 0.1 to 7 pts.mass based on 100 pts.mass of the resin.SELECTED DRAWING: None

Description

  The present invention relates to a phosphor-containing composition and an LED device using the same.

In the field of light emitting diodes (LEDs), it is known to use particulate phosphors for wavelength conversion. The phosphor for wavelength conversion is excited by the wavelength (excitation wavelength) of the emitted light of the LED element, and emits fluorescence having a wavelength different from the excitation wavelength. For example, blue light can be converted into pseudo-white light by covering the light emitting surface of an LED element that emits blue light with a transparent resin in which a phosphor emitting yellow fluorescence is dispersed.
As a transparent resin for dispersing such a phosphor, a method using a silicone resin is known (Patent Documents 1 and 2).

  Patent Document 1 discloses the following method using a silicone resin as a transparent resin for dispersing the phosphor. That is, a composition in which a phosphor is dispersed in a varnish containing an organopolysiloxane, a curing agent and an organic solvent is applied onto a substrate, and the resulting coating film is dried by heating to produce a thermosetting sheet. To do. By disposing the sheet on the surface of the LED element and curing it by heating, the LED element surface can be covered with a silicone resin layer containing a phosphor.

Patent Document 2 includes a phosphor dispersion liquid in which a phosphor is dispersed in an organic solvent and a binder dispersion that does not include a binder, and a binder precursor that does not include a phosphor in which a precursor of a light-transmitting binder is dissolved in an organic solvent. A method of curing a precursor of a light-transmitting binder after alternately applying a liquid on an LED element is described.
Silicone resin precursors, epoxy resin precursors, and translucent ceramic precursors are described as the precursors of the translucent binder.

JP 2013-177553 A International Publication No. 2013/051280

In the methods described in Patent Documents 1 and 2, since an organic solvent is used, it is not environmentally preferable, and a method that does not use an organic solvent or a method that can reduce the amount of the organic solvent used is desired.
The present inventors tried to prepare a phosphor-containing layer by dispersing a phosphor in an aqueous dispersion of a silicone resin, but the obtained phosphor-containing layer was inferior in light resistance. Specifically, coloring occurred when the phosphor-containing layer was irradiated with ultraviolet rays.
Accordingly, when a phosphor-containing layer was prepared by dispersing a phosphor in an aqueous dispersion of a fluororesin composition, coloring sometimes occurred due to irradiation with ultraviolet rays. When the phosphor-containing layer is colored, there is a problem that the color tone of the emitted light from the LED element does not become as designed.

  The present invention relates to a phosphor-containing composition capable of forming a phosphor-containing layer that is excellent in light resistance and is less likely to be colored by irradiation with ultraviolet rays, and an LED device including the phosphor-containing layer formed using the phosphor-containing composition The purpose is to provide.

  As a result of earnestly examining the cause of coloring when the phosphor-containing layer formed by dispersing the phosphor in the aqueous dispersion of the fluororesin composition is irradiated with ultraviolet rays, the present inventors have found that the fluororesin composition When a large amount of an emulsifier is contained in the emulsion, such coloring becomes remarkable, and it has been found that the coloring can be suppressed by reducing the content of the emulsifier.

The present invention includes the following [1] to [5].
[1] A composition for forming a phosphor-containing layer that covers a light emitting surface of an LED element, comprising a resin containing a fluororesin (I), a phosphor, an aqueous medium, and an emulsifier, The phosphor-containing composition, wherein the content is 0.1 to 7 parts by mass with respect to 100 parts by mass of the resin.

[2] The phosphor-containing composition according to [1], wherein the fluororesin (I) includes the following fluororesin (IA).
Fluororesin (IA): a copolymer having a unit (a1) based on a fluoroolefin, a unit (a2) based on an alkyl vinyl ether or an alkyl vinyl ester, and a unit (a3) based on a monomer having a hydrophilic group.

[3] A composition for forming a phosphor-containing layer that covers the light emitting surface of the LED element, comprising a resin containing the fluororesin (I), a phosphor, and an aqueous medium, and no emulsifier. The phosphor containing composition in which the said fluororesin (I) contains the following fluororesin (IB).
Fluororesin (IB): a copolymer having a unit (a1) based on a fluoroolefin, a unit (a2) based on an alkyl vinyl ether or an alkyl vinyl ester, and a unit (a4) represented by the following formula (a4).

[In the formula (a4), R ¹ is a hydrogen atom or a methyl group, R ² and R ³ are each independently an alkylene group having 1 to 10 carbon atoms or a cycloalkylene group having 4 to 10 carbon atoms; ⁴ is a hydrogen atom or —NHZ ¹ Z ² Z ³ (Z ¹ , Z ² and Z ³ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a hydroxyalkyl group having 1 to 6 carbon atoms.) It is essential that at least a part of R ⁴ is —NHZ ¹ Z ² Z ³ , p is an integer of 0 to 8, and q is 0 or 1. ]

[4] The phosphor-containing composition according to any one of [1] to [3], wherein the resin content is 1 to 100 parts by mass with respect to 100 parts by mass of the phosphor.
[5] An LED element and a phosphor-containing layer that covers the light emitting surface of the LED element, and the phosphor-containing layer is coated with the phosphor-containing composition according to any one of [1] to [4] and dried. LED device, which is a layer that has been removed.

By using the phosphor-containing composition of the present invention, it is possible to form a phosphor-containing layer that has excellent light resistance and is less likely to be colored by ultraviolet irradiation.
ADVANTAGE OF THE INVENTION According to this invention, the LED device by which the light emission surface of the LED element was covered with the fluorescent substance content layer excellent in light resistance is obtained.

<Phosphor>
The phosphor used in the present invention is not particularly limited as long as the phosphor can convert the wavelength of the emitted light of the LED element.
For example, a YAG (yttrium, aluminum, garnet) phosphor may be used as a phosphor that emits yellow fluorescence. The YAG phosphor receives blue light (wavelength 420 nm to 485 nm) emitted from the blue LED element and emits yellow light (wavelength 550 nm to 650 nm).

For example, phosphors can be obtained by, for example, 1) mixing an appropriate amount of a fluoride such as ammonium fluoride as a flux into a mixed raw material having a predetermined composition and pressurizing it to obtain a molded body, and 2) placing the obtained molded body in a crucible. It is manufactured by packing and firing in air at a temperature range of 1350 to 1450 ° C. for 2 to 5 hours to obtain a sintered body.
A mixed raw material having a predetermined composition is obtained by sufficiently mixing the oxides of Y, Gd, Ce, Sm, Al, La, and Ga, or compounds that easily become oxides at high temperatures in a stoichiometric ratio. Can do.
Alternatively, the mixed raw material having a predetermined composition is a coprecipitation oxidation obtained by firing a solution obtained by dissolving a rare earth element of Y, Gd, Ce, and Sm in an acid in a stoichiometric ratio and coprecipitating with oxalic acid. It can be obtained by mixing a material with aluminum oxide and gallium oxide.

The type of the phosphor is not limited to the YAG phosphor, and may be another phosphor such as a non-garnet phosphor that does not contain Ce. Silicate phosphors, nitride phosphors, oxynitride phosphors, sulfide phosphors, thiogallate phosphors, aluminate phosphors, and the like can also be used.
The shape of the phosphor is not particularly limited, but is preferably particulate. When the phosphor is particulate, the average particle size of the phosphor is preferably 1 μm or more and 50 μm or less. The larger the particle size of the phosphor, the higher the light emission efficiency (wavelength conversion efficiency). On the other hand, when the particle size of the phosphor is too large, a gap is likely to be generated between the phosphor and the resin in the phosphor-containing layer, and the strength of the phosphor-containing layer may be reduced.
The average particle diameter of the phosphor in the present specification is a volume-based median diameter measured by a Coulter counter method.

<Resin>
The phosphor-containing composition contains a resin, and the resin contains at least a fluororesin (I). You may include resin other than fluororesin (I) in the range which does not impair the effect of this invention.
The content of the resin in the phosphor-containing composition is preferably 1 to 100 parts by mass, more preferably 5 to 50 parts by mass, and particularly preferably 10 to 30 parts by mass with respect to 100 parts by mass of the phosphor. When the content of the resin is in the above range, sufficient light emission efficiency (wavelength conversion efficiency) and good film formability can be obtained in the phosphor-containing layer.
30 mass% or more is preferable, as for the content rate of fluororesin (I) with respect to the whole quantity of resin in a fluorescent substance containing composition, 50 mass% or more is more preferable, and 80 mass% or more is further more preferable. It may be 100% by mass.
As the resin other than the fluororesin (I), a non-fluorine resin such as an acrylic resin, a polyester resin, a melamine resin, a urethane resin, or a silicone resin can be appropriately used.
When the resin in the phosphor-containing composition contains a non-fluororesin, it is preferable that the fluororesin (I) and the non-fluorine resin are present in the same particle as in the composite resin particle (IC) described later. .

<Fluororesin (I)>
The fluororesin (I) is a polymer compound having a fluorine atom in the molecule.
In the present specification, the “unit” means a portion derived from a monomer that exists in the polymer and constitutes the polymer. Moreover, what unitally converted the structure of a unit after polymer formation is also called a unit. “Monomer” means a compound having a polymerizable carbon-carbon double bond.

As the fluororesin (I), a polymer having a unit (a1) based on a fluoroolefin is preferable. A copolymer having a unit (a1) based on a fluoroolefin and a unit based on a monomer other than the fluoroolefin may be used.
As the fluoroolefin, vinyl fluoride, vinylidene fluoride (hereinafter also referred to as “VDF”), chlorotrifluoroethylene (hereinafter also referred to as “CTFE”), tetrafluoroethylene (hereinafter also referred to as “TFE”). ), Hexafluoropropylene (hereinafter also referred to as “HFP”), and the like. A fluoroolefin may be used individually by 1 type, and may use 2 or more types together.
As monomers other than fluoroolefin, perfluoro (alkyl vinyl ether); alkyl vinyl ether or alkyl vinyl ester; monomer having hydrophilic group; both fluorine atom and hydrophilic group other than alkyl vinyl ether or alkyl vinyl ester Other monomers that do not have;
“Perfluoro (alkyl vinyl ether)” means that all of the hydrogen atoms of the alkyl vinyl ether are replaced with fluorine atoms.
Examples of the other monomer having neither a fluorine atom nor a hydrophilic group include olefins such as ethylene, propylene, and isobutylene.

  The fluororesin (I) preferably contains a fluororesin (IA) or (IB) described later. Examples of fluororesin (I) that does not fall under either fluororesin (IA) or (IB) include TFE-perfluoro (alkyl vinyl ether) copolymer, TFE-HFP copolymer, TFE-perfluoro (alkyl vinyl ether). -HFP copolymer, ethylene-TFE copolymer, polyvinylidene fluoride and the like.

[Fluororesin (IA)]
As the fluororesin (I), since it is easily dispersed or dissolved in water, a unit (a1) based on a fluoroolefin and a unit (a2) based on a monomer (a2) which is an alkyl vinyl ether or an alkyl vinyl ester Fluorine resin (IA) which is a copolymer having a unit (a3) based on the monomer (a3) having a hydrophilic group can be preferably used. The fluororesin (IA) does not contain the unit (a4) described later.

The monomer (a2) is preferably a monomer represented by the following formula (a2-1).
^{_{CH 2 = CR 11 (CH 2}} ) j -O- (CO) k R 12 ··· (a2-1)
[Wherein, R ¹¹ is a methyl group or a hydrogen atom, R ¹² is an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group having 4 to 10 carbon atoms, j is an integer of 0 to 8, and k is 0 or 1. . ]
As the monomer (a2), ethyl vinyl ether and cyclohexyl vinyl ether are more preferable because the polymerization reactivity and the glass transition point of the resulting resin are easily adjusted.

The hydrophilic group present in the monomer (a3) is at least one selected from a polyoxyalkylene group, a hydroxyl group, and a carboxyl group. It is preferable to have a polyoxyalkylene group from the viewpoint of the stability of the resulting aqueous dispersion. As the polyoxyalkylene group, a polyoxyethylene group, a polyoxypropylene group, a polyoxybutylene group and the like are preferable.
As the monomer (a3), a monomer represented by the following formula (a3-1) is particularly preferable. “CycloC ₆ H ₁₀ ” represents a 1,4-cyclohexylene group.
_{CH 2 = CHOCH 2 -cycloC 6 H} 10 -CH 2 -O- (CH 2 CH 2 O) n H ... (a3-1)
[Wherein n represents the number of added moles of the oxyethylene group and is an integer of 2 to 40. ]
When the hydrophilic group of the monomer (a3) is a hydroxyl group, the monomer (a3) is preferably hydroxyalkyl vinyl ether or hydroxyalkyl allyl ether, and is selected from hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, and cyclohexane dimethanol monovinyl ether. One or more selected from the above are more preferable.

The content of each unit in the fluororesin (IA) is 30 to 70 mol% for the unit (a1) and 20 to 70 mol% for the unit (2a) with respect to all units constituting the fluororesin (IA). It is preferable that (a3) is 0.1 to 30 mol%, and the total of units (a1), (a2) and (a3) is 70 to 100 mol%.
More preferably, the unit (a1) is 40 to 60 mol%, the unit (2a) is 30 to 55 mol%, the unit (a3) is 0.1 to 20 mol%, the units (a1), (a2), The total of (a3) is 90 to 100 mol%.
The hydroxyl value of the fluororesin (IA) is preferably from 0.1 to 150 mgKOH / g, more preferably from 1 to 100 mgKOH / g.
When the fluororesin (I) contains the fluororesin (IA), the content of the fluororesin (IA) with respect to the fluororesin (I) is preferably 50% by mass or more, more preferably 70% by mass or more, and 90% by mass or more. Further preferred. It may be 100% by mass.

[Fluororesin (IB)]
Since the fluororesin (I) is easily dispersed or dissolved in water even when it does not contain an emulsifier, the unit (a1) based on fluoroolefin and the monomer (a2) that is an alkyl vinyl ether or alkyl vinyl ester are used. A fluororesin (IB) which is a copolymer having a unit (a2) based on and a unit (a4) represented by the following formula (a4) is preferred. The fluororesin (IB) may contain a unit (a3) based on the monomer (a3) having the hydrophilic group.

[In the formula (a4), R ¹ is a hydrogen atom or a methyl group, R ² and R ³ are each independently an alkylene group having 1 to 10 carbon atoms or a cycloalkylene group having 4 to 10 carbon atoms; ⁴ is a hydrogen atom or —NHZ ¹ Z ² Z ³ (Z ¹ , Z ² and Z ³ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a hydroxyalkyl group having 1 to 6 carbon atoms.) It is essential that at least a part of R ⁴ is —NHZ ¹ Z ² Z ³ , p is an integer of 0 to 8, and q is 0 or 1. ]
The monomer (a2) is preferably a monomer represented by the above formula (a2-1), more preferably cyclohexyl vinyl ether.
The unit (a4) is a unit having a carboxy group or a salt thereof at the terminal. The unit (a4) can be obtained, for example, by the following method. That is, by synthesizing a precursor copolymer having a unit having a hydroxyl group at the terminal and reacting the precursor copolymer with a dibasic acid anhydride in an organic solvent, a part of the hydroxyl group is esterified to form a carboxy group. Is introduced (esterification step). Next, the unit (a4) can be obtained by adding a basic compound and water to neutralize at least a part of the carboxy group with the basic compound (neutralization step).
The unit having a hydroxyl group is the same as in the case where the hydrophilic group of the monomer (a3) is a hydroxyl group. As the dibasic acid anhydride, succinic anhydride, glutaric anhydride, itaconic anhydride, phthalic anhydride, maleic anhydride, hexahydrophthalic anhydride and the like are preferable, because they are soluble and easily react with hydroxyl groups. More preferred is succinic anhydride.
As the basic compound, a quaternary ammonium salt or a tertiary amine is used, but a tertiary amine such as triethylamine is preferable.
In the unit (a4), the ratio of R ⁴ being —NHZ ¹ Z ² Z ³ is preferably 30 to 100 mol%, and more preferably 50 to 100 mol%.

The content of each unit in the fluororesin (IB) is such that the unit (a1) is 40 to 60 mol%, the unit (2a) is 3 to 50 mol%, and the unit with respect to all units constituting the fluororesin (IB). It is preferable that (a4) is 0.4 to 7 mol%, and the total of units (a1), (a2), and (a3) is 50 to 100 mol%.
More preferably, the unit (a1) is 55 to 65 mol%, the unit (2a) is 3 to 35 mol%, the unit (a4) is 1 to 5 mol%, and the units (a1), (a2), (a4 ) Is 70 to 100 mol%.
The hydroxyl value of the fluororesin (IB) is preferably 0 to 150 mgKOH / g, more preferably 10 to 100 mgKOH / g.
When fluororesin (I) contains fluororesin (IB), the content of fluororesin (IB) with respect to fluororesin (I) is preferably 50% by mass or more, more preferably 70% by mass or more, and 90% by mass or more. Further preferred. It may be 100% by mass.

[Composite resin particles (IC)]
The resin in the phosphor-containing composition may include composite resin particles (IC) including a fluororesin (I) and a non-fluororesin such as an acrylic resin or a polyester resin. By including an acrylic resin or a polyester resin, physical properties such as transparency or film forming property can be improved.
As the composite resin particles (IC) containing the fluororesin (I) and the acrylic resin, for example, composite polymer particles described in International Publication 2013/047249 can be used.
In the composite resin particles (IC), the content of the fluororesin (I) is preferably 0 to 70% by mass, more preferably 0 to 50% by mass, and further preferably 0 to 30% by mass.

<Emulsifier>
The phosphor-containing composition of the present invention does not contain an emulsifier or a small amount when an emulsifier is contained.
As shown in Examples described later, the light resistance of the phosphor-containing layer formed using the phosphor-containing composition can be improved by reducing the content of the emulsifier in the phosphor-containing composition. it can.
As the emulsifier, a nonionic emulsifier, an anionic emulsifier, and a cationic emulsifier can be appropriately selected. Of these, nonionic emulsifiers are preferred because of the excellent stability of the fluororesin aqueous dispersion.
The ratio of the nonionic emulsifier to the total amount of the emulsifier is preferably 50 to 100% by mass, more preferably 80 to 99% by mass, and particularly preferably 90 to 99% by mass.

The HLB of the emulsifier contained in the phosphor-containing composition of the present invention is 12-18. An emulsifier having an HLB in the above range is excellent in stability in emulsion polymerization at the time of producing a fluororesin and stability of an aqueous fluororesin dispersion.
Nonionic emulsifiers include polyoxyethylene alkyl ethers and polyoxyethylene polycyclic phenyl ethers.
Examples of the anionic emulsifier include sodium lauryl sulfate and ammonium lauryl sulfate.
Examples of the cationic emulsifier include alkyl trimethyl ammonium chloride.
Emulsifiers with HLB less than 12 or greater than 18 are not included in the phosphor-containing composition of the present invention.
In the phosphor-containing composition of the present invention, when the emulsifier is 7 parts by mass or less with respect to 100 parts by mass of the resin, good light resistance in the phosphor-containing layer is obtained. The content of the emulsifier is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, still more preferably 2 parts by mass or less, and particularly preferably 1.5 parts by mass or less with respect to 100 parts by mass of the resin.
On the other hand, the lower limit of the content of the emulsifier is preferably 0.5 parts by mass or more and more preferably 1 part by mass or more with respect to 100 parts by mass of the resin in terms of excellent stability in emulsion polymerization.
When 2 or more types of emulsifiers are contained in a fluorescent substance containing composition, the sum total should just be in said range.

<Aqueous medium>
The phosphor-containing composition of the present invention contains an aqueous medium. By aqueous medium is meant water alone or a mixture of water and a small amount of organic solvent.
When the aqueous medium is a mixture of water and an organic solvent, the content of the organic solvent is 50% by mass or less with respect to the total amount of the medium in the phosphor-containing composition (the remainder excluding the solid content). % By mass or less is preferable, and 1% by mass or less is particularly preferable.

<Phosphor-containing composition>
[First embodiment]
The 1st aspect of the fluorescent substance containing composition of this invention contains resin containing fluororesin (I), fluorescent substance, an aqueous medium, and an emulsifier. In addition to these essential components, other components such as a light stabilizer, a surface conditioner, and a curing agent may be included as necessary within a range not impairing the effects of the present invention. The other component is preferably 10% by mass or less, more preferably 5% by mass or less, and may be zero with respect to the fluororesin (I).
The phosphor-containing composition according to the first aspect is an aqueous dispersion of the fluororesin (I) obtained by obtaining an aqueous dispersion containing an emulsifier and the fluororesin (I) in an aqueous medium by using, for example, an emulsion polymerization method. It is obtained by adding a phosphor to the dispersion and mixing.
In the phosphor-containing composition of the first aspect, 50% by mass or more, preferably 100% by mass of the resin is the fluororesin (I), and the fluororesin (I) preferably contains the fluororesin (IA). .
Alternatively, in the phosphor-containing composition of the first aspect, 50% by mass or more, preferably 100% by mass of the resin is preferably the composite resin particle (IC).

[Second embodiment]
A second aspect of the phosphor-containing composition of the present invention comprises a resin containing a fluororesin (I), a phosphor, and an aqueous medium, the fluororesin (I) contains the fluororesin (IB), and an emulsifier. Not included. In addition to these essential components, other components may be included as required in the same manner as in the first embodiment, as long as the effects of the present invention are not impaired.
In the phosphor-containing composition according to the second aspect, 50% by mass or more, preferably 100% by mass of the resin is the fluororesin (I), and the fluororesin (I) preferably contains the fluororesin (IB). .

The fluororesin (IB) can be produced, for example, by the production method described in International Publication No. 2007/125970. In this method, an aqueous dispersion of fluororesin (IB) containing no emulsifier can be obtained by synthesizing the precursor copolymer by a solution polymerization method without using an emulsifier.
The phosphor-containing composition of the second aspect is obtained by adding and mixing the phosphor to the aqueous dispersion of the fluororesin (IB) containing no emulsifier thus obtained.

<LED device>
The LED device includes at least an LED element and a phosphor-containing layer that covers a light emitting surface of the LED element. In addition, known constituent members such as a sealing material can be appropriately provided in the LED device.
The phosphor-containing layer is formed by applying the phosphor-containing composition of the present invention on the light emitting surface of the LED element and then drying it. Drying is performed to such an extent that the aqueous medium in the phosphor-containing composition is removed. The phosphor-containing layer may not be cured, but may be cured using a known curing agent (crosslinking agent).
The film thickness of the phosphor-containing layer can be appropriately selected depending on the phosphor content, light emission efficiency, and the like, but is usually preferably 1 to 500 μm, more preferably 10 to 300 μm.

Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples.
The monomers used in the examples are as follows.
[Fluoroolefin]
CTFE: Chlorotrifluoroethylene VDF: Vinylidene fluoride TFE: Tetrafluoroethylene HEP: Hexafluoropropylene [alkyl vinyl ether]
EVE: ethyl vinyl ether CHVE: cyclohexyl vinyl ether [monomer having a hydrophilic group]
_{CM-EOVE: CH 2 = CHOCH} 2 -cycloC 6 H 10 -CH 2 O (CH 2 CH 2 O) n H (n is the number average molecular weight of CM-EOVE is 830.)
[Other monomers (monomers having a hydroxyl group)]
HBVE: 4-hydroxybutyl vinyl ether _{CHMVE: CH 2 = CHOCH 2 -cycloC} 6 H 10 -CH 2 OH
[Acrylic resin monomer]
MMA: methyl methacrylate n-BA: n-butyl acrylate AA: acrylic acid

[Production Example 1: Fluororesin aqueous dispersion (1)]
In this example, a fluororesin aqueous dispersion in which the fluororesin (IB) was dispersed in water and no emulsifier was prepared.
In a pressure resistant reactor with a stirrer made of stainless steel with an internal volume of 2500 ml, 590 g of xylene, 170 g of ethanol, 76 g of EVE, 168 g of HBVE, 136 g of CHVE, 11 g of calcium carbonate and perbutyl perpivalate as a polymerization initiator ( 3.5 g of PBPV) was charged and degassed with nitrogen to remove dissolved oxygen in the liquid. Next, 432 g of CTFE was introduced, the temperature was gradually raised, and the polymerization reaction was continued while maintaining the temperature at 65 ° C.
After 10 hours, the reaction was stopped by cooling the reactor with water. After cooling the reaction solution to room temperature, unreacted monomers were purged, and the resulting reaction solution was filtered through diatomaceous earth to remove solids. Next, xylene and ethanol were removed by distillation under reduced pressure to obtain a fluororesin having a hydroxyl group. The hydroxyl value of the fluororesin was 102 mgKOH / g.

Subsequently, in the fluororesin obtained above, a part of the hydroxyl groups of the HBVE unit in the fluororesin obtained above was esterified to introduce a carboxy group, and then neutralized with a basic compound to convert to a unit (a4).
That is, a fluororesin having a hydroxyl group was dissolved in methyl ethyl ketone (MEK) to obtain a solution having a solid content of 60% by mass. To 300 g of the solution, 4.8 g of succinic anhydride and 0.072 g of triethylamine as a catalyst were added and reacted at 70 ° C. for 6 hours for esterification. In the infrared absorption spectrum of the reaction solution, the characteristic absorption of acid anhydride (1850 cm ⁻¹ , 1780 cm ⁻¹ ) observed before the reaction disappeared after the reaction, and the carboxylic acid (1710 cm ⁻¹ ) and ester (1735 cm ⁻ ) were lost. Absorption of ¹ ) was observed. The hydroxyl value of the fluororesin after esterification was 85 mgKOH / g, and the acid value was 15 mgKOH / g.
Next, 4.9 g of triethylamine was added to the esterified fluororesin, and the mixture was stirred at room temperature for 20 minutes to neutralize the carboxylic acid, and 160 g of ion-exchanged water was gradually added.
Thereafter, acetone and methyl ethyl ketone were distilled off under reduced pressure, and 20 g of ion-exchanged water was further added to obtain a fluororesin aqueous dispersion (1) having a solid content concentration of 50% by mass. The aqueous fluororesin dispersion (1) does not contain an emulsifier.
In the obtained fluororesin, the content ratio of units based on each monomer is 15 mol% for EVE units (meaning units based on EVE, the same applies hereinafter), 17 mol% for HBVE units, and 15 mol% for CHVE units. , CTFE unit 50 mol%, unit (a4) 3 mol%.

[Production Example 2: Fluororesin aqueous dispersion (2)]
In this example, an aqueous fluororesin dispersion in which a fluororesin (IA) is dispersed in water containing an emulsifier was prepared.
In an autoclave with a stirrer made of stainless steel with an internal volume of 2500 ml, ion-exchanged water 1280 g, EVE 185 g, CHVE 244 g, CM-EOVE 47 g, CHMVE 194 g, ion-exchanged water 1280 g, potassium carbonate (K ₂ CO ₃ ) 2.0 g, 1.3 g of ammonium persulfate (APS), 67 g of nonionic emulsifier (product name: Newcol-2320, manufactured by Nippon Emulsifier Co., Ltd., HLB value 16), and 1.4 g of anionic emulsifier (sodium lauryl sulfate) were charged. After removing dissolved oxygen in the liquid by degassing with nitrogen, 664 g of CTFE was charged, and a polymerization reaction was performed at 50 ° C. After the reaction for 24 hours, the reactor was cooled with water to stop the reaction, and an aqueous fluororesin dispersion (2) having a solid content concentration of 50% by mass was obtained. The hydroxyl value of the fluororesin was 55 mgKOH / g.
The total content of the emulsifier in the fluororesin aqueous dispersion (2) is 5.1 parts by mass with respect to 100 parts by mass of the resin.
In the obtained fluororesin, the content ratio of units based on each monomer was as follows: EVE unit 22.5 mol%, CHVE unit 17 mol%, CM-EOVE unit 0.5 mol%, CHMVE unit 10 mol%, CTFE The unit is 50 mol%.

[Production Example 3: Fluororesin aqueous dispersion (3)]
67 g of nonionic emulsifier and 1.4 g of anionic emulsifier in Production Example 2 were changed to 1020 g of nonionic emulsifier and 1.4 g of anionic emulsifier. Otherwise in the same manner as in Production Example 2, an aqueous fluororesin dispersion (3) was obtained.
The total content of the emulsifier in the fluororesin aqueous dispersion (3) is 1.6 parts by mass with respect to 100 parts by mass of the resin.
The hydroxyl value of the fluororesin and the content ratio of units based on each monomer are the same as in Production Example 2.

[Comparative Production Example 1: Fluororesin aqueous dispersion (4)]
67 g of nonionic emulsifier and 1.4 g of anionic emulsifier in Production Example 2 were changed to 100 g of nonionic emulsifier and 1.4 g of anionic emulsifier. Otherwise in the same manner as in Production Example 2, an aqueous fluororesin dispersion (4) was obtained.
The total content of the emulsifier in the fluororesin aqueous dispersion (4) is 7.6 parts by mass with respect to 100 parts by mass of the resin.
The hydroxyl value of the fluororesin and the content ratio of units based on each monomer are the same as in Production Example 2.

[Production Example 4: Fluororesin aqueous dispersion (5)]
In this example, an aqueous fluororesin dispersion in which composite resin particles (IC) are dispersed in water containing an emulsifier was prepared.
An aqueous dispersion in which particles of a copolymer having a VDF unit / TFE unit / CTFE unit of 72.1 / 14.9 / 13 (mol%) representing the composition ratio of units based on monomers are dispersed in water 571.4 g (solid content concentration 45.5% by mass) was placed in a glass separable flask having an internal volume of 2.0 L. Thereto, 28.1 g of a nonionic emulsifier (product name: Newcol-707, manufactured by Nippon Emulsifier Co., Ltd., HLB value 12.5) and 59.3 g of water were added and mixed well to prepare an intermediate aqueous dispersion.
Next, in a glass flask having an internal volume of 1.0 L, 208.1 g (80.0 mass%) of MMA, 44.9 g (17.3 mass%) of n-BA, and 7.0 g (2.7 of AA). (Mass%) was added to prepare a monomer solution. The internal temperature of the separable flask was raised to 80 ° C., and the entire amount of the monomer solution was added to the intermediate aqueous dispersion over 3 hours. Simultaneously with the dropping of the monomer solution, the polymerization reaction was allowed to proceed while adding 41.1 g of a 1% by weight aqueous solution of ammonium persulfate (APS), which is a polymerization initiator, in 7 portions every 30 minutes. Five hours after the start of polymerization, the reaction solution was cooled to room temperature to stop the reaction, and a fluororesin aqueous dispersion (5) having a solid content concentration of 52.0% by mass was obtained.
The obtained fluororesin is a composite resin particle containing a fluororesin and an acrylic resin, and the composition of the acrylic resin portion in the composite resin particle is MMA / n-BA / AA = 80.0 / 17.3 / 2. 7 (mass ratio). Moreover, mass ratio (fluororesin / acrylic resin) of the fluororesin part and the acrylic resin part in the obtained composite resin particles was 50/50.
The total content of emulsifiers in the fluororesin aqueous dispersion (5) is 5.4 parts by mass with respect to 100 parts by mass of the resin.

[Comparative Production Example 2: Silicone resin aqueous dispersion (6)]
In this example, an aqueous silicone resin dispersion in which a silicone resin is dispersed in water containing an emulsifier was prepared.
Silicone flake resin having a number average molecular weight of 1200 and a specific gravity of 1.25 (product name: Xiameter, RSN-6018, manufactured by Dow Corning), 16 g of spherical glass beads having a particle diameter of 3 mm (Fisher), and nonionic surface activity 1.7 g of the agent (product name: Pluronic, F-108, manufactured by BASF, HLB value 24) was weighed in this order to a maximum of 100 cups. The cup was sealed, placed in a mixer (product name: DAC-150 SpeedMixer, manufactured by Synergy Devices), the cup was rotated at maximum speed (3450 rpm) for 2 minutes, removed from the mixer, and allowed to stand still for 5 minutes. The cup was returned to the mixer and rotated for an additional 1 minute at maximum speed. To the resulting mixture, 28 g of deionized water was added in five portions. The cup was rotated for 25 seconds after each addition of water. The addition amount of the deionized water of the 1st time-the 5th time was 2g, 3g, 5g, 8g, and 10g in order. Thus, a silicone resin aqueous dispersion (6) having a silicone content of 50% by mass was obtained.
The total content of the emulsifier in the aqueous silicone resin dispersion is 5.0 parts by mass with respect to 100 parts by mass of the silicone resin.

[Examples 1 to 4, Comparative Examples 1 and 2]
As shown in Table 1, a phosphor (YAG) having an average particle diameter of 5 μm was added to the aqueous dispersions (1) to (6) obtained in Production Examples 1 to 4 and Comparative Production Examples 1 and 2, and 60 ° C. The phosphor-containing composition was prepared by stirring with a planetary mixer that had been warmed to a low temperature. The content of the resin in the phosphor-containing composition was 30 parts by mass with respect to 100 parts by mass of the phosphor.
The obtained phosphor-containing composition is coated on a glass substrate with a film coater so that the thickness after drying is 50 μm, and dried by heating at 80 ° C. for 60 minutes to form a phosphor-containing layer. did.

[Evaluation of light resistance]
The phosphor-containing layer on the glass substrate obtained in each example was subjected to UV irradiation (30 mW) for 24 hours using a UV irradiation device (product name: eye ultraviolet curing device, manufactured by Eye Graphics). The film after UV irradiation was visually observed and light resistance was evaluated according to the following criteria. The results are shown in Table 1.
A: No coloring is observed in the phosphor-containing layer.
◯: Slight coloration is observed in the phosphor-containing layer, but there is no problem.
X: Remarkable coloring is observed in the phosphor-containing layer, which is a problematic level.

As shown in the results of Table 1, the phosphor-containing layers formed using the phosphor-containing compositions of Examples 1 to 4 have good light resistance and are not easily colored by ultraviolet irradiation. there were.
On the other hand, in Comparative Example 1 in which the phosphor was dispersed in the fluororesin aqueous dispersion containing a large amount of emulsifier, photodegradation was likely to occur and coloring was caused by irradiation with ultraviolet rays.
Further, Comparative Example 2 in which a phosphor was dispersed in an aqueous dispersion of a silicone resin was also susceptible to photodegradation, and coloring was caused by irradiation with ultraviolet rays.
In particular, when Examples 2 and 3 and Comparative Example 1 are compared, it can be seen that light resistance is improved when the content of the emulsifier is reduced.

Claims (5)

A composition for forming a phosphor-containing layer covering a light emitting surface of an LED element,
A resin containing a fluororesin (I), a phosphor, an aqueous medium, and an emulsifier,
The phosphor containing composition whose content of the said emulsifier is 0.1-7 mass parts with respect to 100 mass parts of resin. The phosphor-containing composition according to claim 1, wherein the fluororesin (I) comprises the following fluororesin (IA).
Fluororesin (IA): a copolymer having a unit (a1) based on a fluoroolefin, a unit (a2) based on an alkyl vinyl ether or an alkyl vinyl ester, and a unit (a3) based on a monomer having a hydrophilic group. A composition for forming a phosphor-containing layer covering a light emitting surface of an LED element,
A resin containing a fluororesin (I), a phosphor, and an aqueous medium, without an emulsifier,
The phosphor containing composition in which the said fluororesin (I) contains the following fluororesin (IB).
Fluororesin (IB): a copolymer having a unit (a1) based on a fluoroolefin, a unit (a2) based on an alkyl vinyl ether or an alkyl vinyl ester, and a unit (a4) represented by the following formula (a4).

[In the formula (a4), R ¹ is a hydrogen atom or a methyl group, R ² and R ³ are each independently an alkylene group having 1 to 10 carbon atoms or a cycloalkylene group having 4 to 10 carbon atoms; ⁴ is a hydrogen atom or —NHZ ¹ Z ² Z ³ (Z ¹ , Z ² and Z ³ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a hydroxyalkyl group having 1 to 6 carbon atoms.) It is essential that at least a part of R ⁴ is —NHZ ¹ Z ² Z ³ , p is an integer of 0 to 8, and q is 0 or 1. ]   The phosphor-containing composition according to any one of claims 1 to 3, wherein the resin content is 1 to 100 parts by mass with respect to 100 parts by mass of the phosphor. An LED element and a phosphor-containing layer that covers the light emitting surface of the LED element;
The LED device in which the phosphor-containing layer is a layer obtained by applying and drying the phosphor-containing composition according to any one of claims 1 to 4.